NorthBay Adventure is just the kind of small business that could be expected to buy medical insurance for workers under health act rules taking effect in 2014. But Executive Director George Comfort says that’s not likely to happen.

Instead, NorthBay became self-insured last year, paying most workers’ health costs directly, a practice more typical of large employers. The decision to self-insure was about free choice, savings and what’s best for his company, Comfort says.

But others see it as a threat to the Affordable Care Act. As more small employers such as NorthBay avoid the act’s requirements through self-coverage, small-business marketplaces intended to cover millions of Americans could break down and become unaffordable, they say.